Thanks again for the info. I'm learning, but slowly. I have a community college a couple of miles away from my house. I'm going to check and see if they have any Music Theory 101 courses I could take.
Now, to this:
C minor with an added major 7th [C Eb G B] or any similar chord in another key sounds very strange. I can't say I know of any song which has this chord.
Interstingly enough, this was the subject of my first post on the Chordie forums. You were involved in the discussion. (Not that I would expect you to remember that.)
Apparently Tom Petty's song "Into the Great Wide Open" uses Emmaj7 in a rundown between Em and Em7, which is just about the only way it "works" as a chord. At the time I was calling it Em#7, until SouthPaw ID'ed it as Emmaj7 in post #11 of that thread.
I now use the same chord progression for sections of "Gentle on my Mind".